Switchgear



Fig. Z.

SWITCHGEAR L. R. LUDWIG Erm.

Filed March 9, 1940 Jan. 5, 1943.

Patented Jan. 5, 1943 SWITCHGEAR Leon R. Ludwig, Forest Hills, and Benjamin P.

Baker, Turtle Creek, Pa., assignors to WestinghouseElectricv & Manufacturing Company, East Pittsburgh, 1a a corporation of Pennsylvania Application Marchi), 1940, Serial No. 323,215

7 Claims.

Our invention relates, generally, to switchgear and, more particularly, to switchgear of the enclosed or cubicle type.

Ank object of our invention, generally stated, is to provide enclosed switchgear which shall be simpleand eincient in operation and which may be economically manufactured and installed.

A more specic object of our invention is to provide enclosed switchgear suitable for housing a. circuit interrupter of the air-blast type.

Another object ofour invention is to provide forv the proper isolation and insulation of the various parts of a compressed air circuit breaker.

A further object of our invention is to provide for safely discharging the gases formed during the interruption of a circuit by a circuit breaker of the air-blast type. v

Still another object of our invention is to provide mulers for an air-blast circuit breaker.

A still further object of our invention is to provide removable arc chambers for an enclosed circuit breaker of the air-blast type.

Other objects of our invention willbe explained fully` hereinafter or will be apparent to those skilled in the art.

In accordance with our invention, a circuit breaker of the air-.blast type isdisposed in a cell or cubicle which is subdivided into a plurality of compartments or sections for housing different parts of the breaker. Access to the various sections is gained through doors which may be opened for inspection and maintenance of the breaker equipment. When the` breaker is in the cubicle, the arc chambers are readily available for inspection by simply drawing them forward, the breaker remaining in the cubicle. An expansion compartment containing muftlers is provided in the cubicle above the arc chambers for receiving the gases discharged from the arc chambers during the interruption of' an arc.

For a fuller understanding of the nature and objects of our invention, reference` may be had to the following detailed description, taken in conjunction with the accompanying drawing in which:

Figure 1 is a View, partially in side elevation and partially in section of a metal-enclosed switchgear cubicle embodying our invention; and

Fig. 2 isa side view, partially in front elevation and partially in section, of the structure shown in Eig. 1.

Referring to the drawing, and particularly to Figure 1, the structure shown therein comprises a cell or cubicle. I-l'I, having a rear wall II and two pairs of doors I2 and I3 disposed at the front of the cubicle, for housing a circuit breaker I4 of the air-blast type, such as disclosed in the copending application of L. R. Ludwig, H. L. Rawlins and B. P. Baker, Serial No. 313,736, iiled January 13, 1940. As illustrated in the drawing, the cubicle I0 is preferably made of sheet steel. However, if desired, the breaker I4 may be enclosed in a concrete cell.

As shown, the cubicle I0 is divided by horizontally disposed barriers I5 and IB into a lower compartment I 'I for housing an air tank and operating mechanism I8 for the circuit breaker I4; an intermediate compartment I9 for contact members 2| .and 22 and arc chambers 23 of the circuit breaker; and an upper compartment 24 into which the gases from the arc chambers 23 are discharged.

As shown in Fig. 2, the intermediate compartment I9 is subdivided by vertically disposed insulating barriers 25 and 26 into three compartments, one of which encloses each pole of the circuit breaker I4, thereby separating the contact members and arc-chute for each pole of the breaker from the other poles.

The contact members 2I and 22 and the arc chambers 23 of the circuit breaker are mounted on the tank I8 by means of insulating supporting members 2'I and 28. The member 2l 'also serves as a pipe for conducting compressed air from the tank I8 to the arc chamber 23 where it is utilized in interrupting the arc drawn between the contact members 2l and 22. The movable contact members 22 are actuated by rods 29 which connect the operating mechanism to the movable contact members. The Afixed contact member 2| is connected to a. terminal 3I mounted on the rear Wall II of the cubicle. Likewise, the movable contact member 22 is connected to a terminal 32 also mounted on the rear wall of the cubicle. The terminals 3l and 32 are available for making suitable electrical connections to the circuit breaker.

With the circuit breaker in its normally operating position, the two doors I2 at the bottom and front of the housing may be opened for inspection and maintenance of the operating mechanism and other mechanical parts which are at ground potential. The center section in which the contact members and the arc chambers are located is made available by opening the upper doors I3. The third or top section which contains mufflers 33 and into which the gases are discharged is also reached by opening the upper doors I3.

Each phase is provided with an adequate muffier 33 in addition to the arc chamber 23 for preventing the escape of ionized llame and reducing noise. As shown in Fig. 2, each muffler 33 comprises a box having sides 34 fitting over the upper end of the arc chamber 23 which extends through the barrier i6. A mixing chamber 35 is provided in the lower part of each muffler for receiving the gases fro-1n the arc chamber 23.

As shown in Fig. 1, each arc chamber is provided with a plurality of arc splitters 36 which generate a gas during the interruption of the arc. The arc is first drawn next to the fixed contact member and the gas generated from the arc splitters nearest the xed contact is hotter than that generated by the splitters nearest the moving contact member. The arc splitters are so disposed in the arc chamber that the -hot gas from the vicinity of the xed contact member 2l ofthe circuit breaker cannot mix with the relatively cool gas from the vicinity of the ,movable contact member 22 while the gas is passing through the arc chamber. Therefore, the mixing chamber 35 allows the hot gas from the section of the arc-chute which is working hardest to be mixed with the cool gas from the section next to the moving contact which is not working so hard, thereby lowering the temperature of the hottest gases.

Each one of the mulers 33 is also provided with alternate layers of relatively ne mesh wire screen 31 and perforated metal plates 38. As shown in Fig. 2, a series of pairs of these plates is disposed in spaced relation at the top of each muler. The muillers discharge the gases from the arc chambers into the exhaust compartment 24 through the wire screen and perforated plates which extract additional heat from the gases. The gases which are thus discharged, are cool enough to preclude hash between phases.

However, the gases from all three arc chambers are discharged into one common compartment 24 so that with a three-phase fault, where one phase gets a greater asymmetry and a full half-cycle of arcing whereas another phase opens more fortuitously, the full volume of the space above the mulTlers is available to the one working the hardest. Likewise, in a single phase operation where full voltage and current may be opened on a single pole, this pole will have the entire volume of the compartment 24 to discharge into and thus prevent any external demonstration of name and reduces the noise. The gases are permitted to escape from the compartment 24 through a plurality of louvers 39 provided in the front of the housing.

Furthermore, by making the upper compartment 24 of the cubicle approximately twice the volume of air used in a single three-phase operation, it may be made capable of receiving all of the air together with the gas which is generated from the arc-chutes as the result of the arc without making the pressure in this chamber rise to a prohibitive level. Thus, by way of example, if the air consumption of the breaker is from l5 to 20 cubic feet for each operation and the gas generated in the arc chambers is about the same, the volume of the expansion chamber 24 should be about 40 cubic feet. thereby permitting the use of relatively small escapements for gas to the outside of the cubicle.

The interphase vertical barriers 25 and 26 are so mounted between the horizontal barriers l5 and I6 that they may be readily removed, by drawing them forward, -for inspection of the breaker parts, Likewise, the arc chambers 23 are also readily available for inspection by drawing them forward. Each one of the arc chambers 23 may be removed from the supporting members 2l and 28 by removing bolts 4l to detach the arc chamber from the breaker, the chamber may then be slid forward along the upper barrier` l5 which is slotted to receive the are chamber. The contact members and other essential live parts of the breaker are opened for inspection or maintenance when the arc chamber is removed, thereby making it unnecessary to remove the complete breaker unit from the housing. However, if desired, the breaker unit may be mounted on wheels and the complete unit, including the arc chambers, withdrawn from the housing, in which case it is not necessary to detach the arc chambers from the breaker.

From the foregoing description, it is apparent that we have provided for housing a circuit breaker of the air-blast type in an economical manner both from a standpoint of the space and the material required. We have also provided for the safe and emcient operation of the breaker since all parts are properly isolated and insulated in the housing. Furthermore, provision is made for the proper cooling and expansion of the gases discharged from the air-blast breaker during its operation. Also, the various parts of the breaker are readily available for inspection and maintenance.

Since numerous changes may be made in the above described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is contended that all matter contained in the foregoing description or shown in'the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. The combination with a multi-phase airblast circuit breaker comprising an operating mechanism, contact members and an arc chamber for each phase, of a unitary housing for enclosing the circuit breaker, said housing comprising an isolated lower compartment for the operating mechanism, an isolated intermediate compartment for the contact members and arc chambers and an isolated upper compartment for the expansion of gases from all of said arc chambers, and an enclosed muiller disposed in the upper compartment over the top of each arc chamber, each muler having a mixing chamber for receiving the 'gases from the arc chamber and a plurality of perforated plates disposed above the mixing chamber through which said gases pass into said upper compartment.

2. The combination with a multi-phase airblast circuit breaker comprising an operating mechanism, contact members and an arc chamber for each phase, of a unitary housing for enclosing the circuit breaker, said housing comprising Van isolated lower compartment for the operating mechanism, an isolated intermediate compartment for the Contact members and arc chamber and an isolated upper compartment for the expansion of gases from all of said arc chambers, and an enclosed muler disposed in the upper compartment over the top of each arc chamber, each muffler having a mixing chamber for receiving the gases from the arc chamber and a plurality of alternate layers of relatively zineV mesh wire screen and perforated metal plates disposed above the mixing chamber through which said gases pass into said upper compartment.

3. In a multi-phase switchgear unit, in Combination, a multi-pole air-blast circuit breaker comprising an operating mechanism, a plurality of contact members and an individual arc chamber having a plurality of spaced plates therein for each pole, a unitary housing for enclosing the circuit breaker, said housing comprising an isolated lower compartment for the operating mechanism, an isolated intermediate compartment for the contact members and arc chambers and an isolated upper compartment for the expansion of gases from all of said arc chambers, and an individual enclosed muffler for each arc chamber, said mufflers being disposed in said upper compartment at the tops of said arc chambers to receive the gases from the chambers and discharge them into said upper compartment.

4. In a multi-phase switchgear unit, in combination, a multi-pole air-blast circuit breaker comprising an operating mechanism, a plurality of contact members and an individual arc chamber having a plurality of spaced plates therein for each pole, a unitary housing for enclosing the circuit breaker, said housing comprising an isolated lower compartment for the operating mechanism, an isolated intermediate compartment for the contact members and arc chambers and an isolated upper compartment for the eX- pansion of gases from all of said arc chambers, and an individual enclosed mufer for each arc chamber, said muiflers being dispose-d in said upper compartment at the tops of said arc chambers to receive the gases from the chambers, all of said muffiers being disposed to exhaust said gases into said upper compartment.

5. In a multi-phase switchgear unit, in combination, a multi-pole air-blast circuit breaker comprising an operating mechanism, a plurality of contact members and an individual arc chamber having a plurality of spaced plates therein for each pole, a unitary housing for enclosing the circuit breaker, said housing comprising an isolated lower compartment for the operating mechanism, an isolated intermediate compartment for the contact members and arc chambers and an isolated upper compartment for the expansion of gases from all of said arc chambers, an individual enclosed muiller for each arc chamber, said muiilers being disposed in said upper compartment at the tops of said arc chambers to receive the gases from the chambers, all of said mulers being disposed to eXhaust said gases into said upper compartment, and means for Ventilating said upper compartment to permit the escapement of said gases.

6. The combination with a multi-phase airblast circuit breaker comprising an operating mechanism, contact members for each phase disposed above the operating mechanism and an arc chamber for each phase extending above the contact members, of a unitary housing for enclosing the circuit breaker, said housing comprising an isolated lower compartment for the operating mechanism, an isolated intermediate compartment disposed above the lower compartment for the contact members and arc chambers and an isolated upper compartment disposed above the intermediate compartment for the expansion of gases from all of said arc chambers, and an enclosed muffler disposed at the top of each arc chamber for receiving the gases from the chamber and discharging them into said upper compartment.

'7. In a multi-phase switchgear unit, in combination, a multi-pole air-blast circuit breaker having a plurality of contact members and an individual arc chamber having a plurality oi spaced plates therein for each pole, a unitary housing for enclosing the circuit breaker, said housing comprising a lower compartment for the contact members and arc chambers and a single upper compartment for the expansion of gases from all of said arc chambers, and an individual enclosed muflier for each arc chamber, one of said mufflers being disposed at the top of each arc chamber to receive the gases from the chamber, all of said muiiiers being disposed to exhaust said gases into said upper compartment.

LEON R. LUDWIG. BENJAMIN P. BAKER.. 

